Riding inside the dimly lit cargo hold of the armored truck was like being transported inside a cellfor solitary confinement. Langdon fought the all too familiar anxiety that haunted him in confinedspaces. Vernet said he would take us a safe distance out of the city. Where? How far?

　　Langdon's legs had gotten stiff from sitting cross-legged on the metal floor, and he shifted hisposition, wincing to feel the blood pouring back into his lower body. In his arms, he still clutchedthe bizarre treasure they had extricated from the bank.

　　"I think we're on the highway now," Sophie whispered.

　　Langdon sensed the same thing. The truck, after an unnerving pause atop the bank ramp, hadmoved on, snaking left and right for a minute or two, and was now accelerating to what felt like topspeed. Beneath them, the bulletproof tires hummed on smooth pavement. Forcing his attention tothe rosewood box in his arms, Langdon laid the precious bundle on the floor, unwrapped his jacket,and extracted the box, pulling it toward him. Sophie shifted her position so they were sitting sideby side. Langdon suddenly felt like they were two kids huddled over a Christmas present.

　　In contrast to the warm colors of the rosewood box, the inlaid rose had been crafted of a pale wood,probably ash, which shone clearly in the dim light. The Rose. Entire armies and religions had beenbuilt on this symbol, as had secret societies. The Rosicrucians. The Knights of the Rosy Cross.

　　"Go ahead," Sophie said. "Open it."Langdon took a deep breath. Reaching for the lid, he stole one more admiring glance at theintricate woodwork and then, unhooking the clasp, he opened the lid, revealing the object within.

　　Langdon had harbored several fantasies about what they might find inside this box, but clearly hehad been wrong on every account. Nestled snugly inside the box's heavily padded interior ofcrimson silk lay an object Langdon could not even begin to comprehend.

　　Crafted of polished white marble, it was a stone cylinder approximately the dimensions of a tennisball can. More complicated than a simple column of stone, however, the cylinder appeared to havebeen assembled in many pieces. Six doughnut-sized disks of marble had been stacked and affixedto one another within a delicate brass framework. It looked like some kind of tubular, multiwheeledkaleidoscope. Each end of the cylinder was affixed with an end cap, also marble, making itimpossible to see inside. Having heard liquid within, Langdon assumed the cylinder was hollow.

　　As mystifying as the construction of the cylinder was, however, it was the engravings around thetube's circumference that drew Langdon's primary focus. Each of the six disks had been carefullycarved with the same unlikely series of letters—the entire alphabet. The lettered cylinder remindedLangdon of one of his childhood toys—a rod threaded with lettered tumblers that could be rotatedto spell different words.

　　"Amazing, isn't it?" Sophie whispered.

　　Langdon glanced up. "I don't know. What the hell is it?"Now there was a glint in Sophie's eye. "My grandfather used to craft these as a hobby. They wereinvented by Leonardo da Vinci."Even in the diffuse light, Sophie could see Langdon's surprise.

　　"Da Vinci?" he muttered, looking again at the canister.

　　"Yes. It's called a cryptex. According to my grandfather, the blueprints come from one of DaVinci's secret diaries.""What is it for?"Considering tonight's events, Sophie knew the answer might have some interesting implications.

　　"It's a vault," she said. "For storing secret information."Langdon's eyes widened further.

　　Sophie explained that creating models of Da Vinci's inventions was one of her grandfather's best-loved hobbies. A talented craftsman who spent hours in his wood and metal shop, Jacques Saunièreenjoyed imitating master craftsmen—Fabergé, assorted cloisonne artisans, and the less artistic, butfar more practical, Leonardo da Vinci.

　　Even a cursory glance through Da Vinci's journals revealed why the luminary was as notorious forhis lack of follow-through as he was famous for his brilliance. Da Vinci had drawn up blueprintsfor hundreds of inventions he had never built. One of Jacques Saunière's favorite pastimes wasbringing Da Vinci's more obscure brainstorms to life—timepieces, water pumps, cryptexes, andeven a fully articulated model of a medieval French knight, which now stood proudly on the deskin his office. Designed by Da Vinci in 1495 as an outgrowth of his earliest anatomy andkinesiology studies, the internal mechanism of the robot knight possessed accurate joints andtendons, and was designed to sit up, wave its arms, and move its head via a flexible neck whileopening and closing an anatomically correct jaw. This armor-clad knight, Sophie had alwaysbelieved, was the most beautiful object her grandfather had ever built... that was, until she had seenthe cryptex in this rosewood box.

　　"He made me one of these when I was little," Sophie said. "But I've never seen one so ornate andlarge."Langdon's eyes had never left the box. "I've never heard of a cryptex."Sophie was not surprised. Most of Leonardo's unbuilt inventions had never been studied or evennamed. The term cryptex possibly had been her grandfather's creation, an apt title for this devicethat used the science of cryptology to protect information written on the contained scroll or codex.

　　Da Vinci had been a cryptology pioneer, Sophie knew, although he was seldom given credit.

　　Sophie's university instructors, while presenting computer encryption methods for securing data,praised modern cryptologists like Zimmerman and Schneier but failed to mention that it wasLeonardo who had invented one of the first rudimentary forms of public key encryption centuriesago. Sophie's grandfather, of course, had been the one to tell her all about that.

　　As their armored truck roared down the highway, Sophie explained to Langdon that the cryptexhad been Da V............